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SARS CoV-2 IgM and IgG antibodies amongst blood donors in Nigeria

Emmanuel Nna 1, Ijeoma Ifeorah 2,4, Uchenna Okeke 3, Emo Ivo 5, Ojor Ayemoba 5, Thairu Yunusa 6, Ogbeche Ochagu 7, Ngozi Ugwu1, 10, Henrietta Okafor 9, Amaka Nnamani 4, Tochukwu Omenma 4, Nneka Iloanusi 4, Osita Okonkwo 4 and Ifeoma Okoye 4

1Safety Molecular Pathology Laboratory, The Molecular Pathology Institute, 44 Rangers Avenue, Independence Layout, Enugu; 2Department of Medical Laboratory Sciences, University of Nigeria, Enugu Campus, Enugu; 3Laboratory Services, Nigerian Navy Reference Hospital, Calabar, Cross River State; 4University of Nigeria Centre for Clinical Trials (UNNCECT), Enugu; 5Defence Reference Laboratory, Ministry of Defense, Abuja; 6Department of Microbiology, University of Abuja, Abuja; 7Nigerian Navy Medical Services, Abuja; 9Department of Paediatrics, University of Nigeria, Enugu Campus, Enugu State; 10Department of Hematology, Ebonyi State University, Abakaliki, Ebonyi State.

Background: Nigeria, the most populous country in Africa could carry the most onerous burden of SARS-CoV-2 if more effective precautions against the virus are not continuously enforced. Speculations exist that the country currently experiences a steady increase in the rate of community spread of COVID-19 as researchers in the country continue to see increasing evidence of infections, yet accurate information on the burden of infection is lacking. We aimed to determine the sero-prevalence of SARS CoV-2 IgM and IgG in screened blood donors in two selected cities in Nigeria.

Method: A total of 213 blood samples from screened, accepted and consenting blood donors were tested for both SARS CoV-2 IgM and IgG antibodies using NOVATECH ELISA kits from Eurofins Germany. Of the 213 blood donors, 96% were males while 4 % were female. The age range for the blood donors were 21- 48 years, median age was 33years. ELISA assay was carried out following the manufacturer’s protocol. Results were calculated and expressed in Nova Tech Units (NTU) as follows: > 11 NTU: Positive for the specific antibody, < 9 NTU: Negative for the specific antibody, 9-11 NTU: Equivocal for the specific antibody as per manufacturer’s instructions. Data were analyzed in GraphPad Prism version 9 (www.graphpad.com).

Result

Of the 213 blood donors studied, 48 (42 %; 95% CI: 34 – 52%) were positive for IgG with a median antibody level of 19 NTU; 46 (41 %; 95% CI: 32-50 %) were positive for IgM level with a median antibody level of 5 NTU. Only eleven (11%; 95 % CI: 05 –17%) donors were equivocal (indeterminate) for SARS CoV-2 IgG, with a median antibody level of 10 NTU. Also, twenty-one (19%; 95% CI: 12 -27%) donors had equivocal titers (indeterminate) for SARS CoV-2 IgM, with a median antibody level of 10 NTU.

Conclusion: Nearly a half of accepted blood donors in Nigeria have been exposed and developed antibodies to SARS-CoV-2. This result confirms the suspicion of local researchers that SARS-CoV-2 infection is widely spread in Nigeria and mostly asymptomatic in nature. The implication of this high seroprevalence of SARS-CoV-2 antibodies in the study population in relation to COVID 19 control and therapeutics remains to be explored.